1. Field of the Invention
The present invention relates to a reel for winding recording tape thereon, such as magnetic tape or the like mainly used as a recording/reproducing medium for a computer or the like.
2. Description of the Related Art
There has been known a recording tape cartridge whose reel winding thereon a magnetic tape is received in a case, as an external recording medium for a computer or the like. The reel has a hub forming an axial portion thereof and winding a magnetic tape around the outer periphery thereof, and top and bottom flanges respectively disposed at the ends of the hub in an axial direction and extending outwards in a radial direction.
Traditionally, a recording tape cartridge is known that a recording tape, such as a magnetic tape used as a data recording/reproducing medium for a computer or the like, is wound over a single reel so that the reel can be rotatably received in a synthetic resin case. The recording tape has a distal end (free end) provided with a leader member, e.g. a leader pin, a leader tape or a leader block. The leader member is to be pulled out through an opening of the recording tape cartridge by a pulling-out portion provided on a drive device side so that the recording tape, secured to the leader member, can be wound onto the take-up reel provided on the drive device side.
In the reel of such a recording tape cartridge, the recording tape is usually wound around the outer peripheral surface of the hub. The hub is provided with top and bottom flanges at the top and bottom thereof. Due to the top and bottom flanges, the vertical position of the recording tape can be controlled, and a favorable winding shape can be maintained, thus improving the running stability of the tape. Furthermore, excessive damage can also be prevented when the cartridge is not in use.
The hub is frequently formed in a cylindrical shape having a base that is open at one side in an axial direction and closed at the other side. Due to the winding pressure of the magnetic tape, the open end side of low strength of a hub formed in such a cylindrical shape with a base tends to deform. When the hub is deformed in this manner, the flange provided on the open end side of the hub deforms in a contact direction towards an end portion (edge) in a width direction of the magnetic tape.
Consequently, to prevent the hub from deforming, a structure wherein the hub is reinforced with a metal ring at its inner periphery has been proposed, as disclosed in the Japanese Patent Application Laid-Open (JP-A) Nos. 2004-14022 and 2005-116163. If, by insert molding, the hub and the bottom flange are integrated, and a metal ring is provided at the inner periphery side of the hub, the need to connect a resin portion of the outer periphery side of the hub to the bottom flange results in a single resin layer disposed at an end portion of the metal ring in an axial direction of the hub.
Because the metal ring is not present in the single resin layer, a low rigid region occurs in a part of the hub. In case a low rigid region is caused in a part of the hub in this manner, the tape undergoes an uneven force from the hub upon tightly winding thereof, thus raising a concern of tape characteristic deterioration. Besides, on the hub side, stress concentration occurs at the boundary between the metal ring and the single resin layer, thus raising a concern of crack occurrence in the single resin layer at around the metal ring.